The Struts Framework is a standard for developing well-architected Web applications. Based on the Model-View-Controller (MVC) design paradigm, it distinctly separates all three levels (Model, View, and Control). It also offers the following features: [Source: Struts Visual Tutorials]

Open source

Implements the JSP Model 2 Architecture

Stores application routing information and request mapping in a single core file, struts-config.xml

The Struts Framework, itself, only fills in the View and Controller layers. The Model layer is left to the developer.